Cement Energy and Environment

-, .. sequestration was microbial carbon capture cells (MCCs). Cyanobacteria were grown in photobiocathode in dual-chambered flat plate mediator-less MFCs separated by an anion exchange membrane. The performance of the MCC with Anabaena purged with C02-air mixture was compared with that of a conventional cathode purged with air only. A maximum power density of 57.8 mW/m2 was observed when 5 per cent (v/v) C02-air mixture was used. Algal biomass was also used as substrate in biohydrogen production. Acid-heat pretreated Chiarella sorokiniana biomass gave maximum hydrogen production of 2.68 mol mol-1 of hexose under thermophilic dark fermentation. Algal biomass from two-stage cultivation was used for biodiesel production. Under mixotrophic growth, maximum lipid content obtained was 58±0.34 per cent w/w of DCW. Phycocyanin and related phycobilin proteins were found to have antioxidant, anti-inflammatory, anti-viral, anti-cancer, cholesterol lowering effects, neuroprotective and hepatoprotective properties and are present in Cyanobacteria. An effort was made to extract these valueadded products that have an industrial application from Nostoc sp. Under green light regime and suitable nitrate concentration, the maximum yield of phycobilin protein (0.132 mg/mg of dry cell mass) was observed. In recent years, microbial fuel cell (MFC)-based technologies have turned out to be promising technologies for direct energy production from various wastewaters. However, numerous hurdles need to be overcome to make this technology economically feasible and suitable for field applications. In this regard, IIT– Kharagpur has focussed on improving the performance, reducing the construction cost, and expanding the application scopes of MFC-based technologies collectively known as bioelectrochemical systems. Lowcost materials for the anode, cathode, and membrane in MFCs were studied to increase the power performance using complex wastewaters as substrate. Catalytic enhancement with MnC0204 in the presence of polypyrrole (PPy) on carbon cloth cathode showed maximum potential reaching power densities of 10.2 W m-3 using low-cost KOH doped PVAPDDA anion exchange membrane. The IIT-Kharagpur team has also exploited MFCs as a secondary stage treatment process by linking it with dark fermentation processes for enhanced energy recovery. Their experimental results indicated overall energy recovery of 33 per cent. Feasibility of power generation and hydrogen production in a microbial electrolysis cell was also ~ Rgure 2: Integration of various forms of energy systems studied using wastes like sewage sludge. The maximum hydrogen yield of 4.5 mmol H2 g-1 CODreduced was achieved at 1.0 V. Using MFCs as portable power sources will need development of cost-effective, selfsustainable, small sized MFCs with lower start-up times, which can generate sustained power for longer periods of time. Although micro-sized MFCs are already developed, the requirement of syringe pumps or other flow distribution systems makes it unpractical to be used in remote locations to power devices. Hence, a paper based air-breathing microbial fuel cell was developed using Shewanella putrefaciens as biocatalyst which has an instant start-up. The developed device could generate a maximum power of 3.5 ~W indicating the potential of the device as a power source in remote locations. IITKharagpur also developed microbial carbon capture cells (MCCs) with Cyanobacteria as photobiocathode and achieved power densities 100.1 mW m-2 thereby providing simultaneous power generation, carbon dioxide sequestration, and wastewater treatment. Currently, the group is focussing on scale-up studies broadening the outlook of this technology. 53